Record Details
Relation of nitrogenous substances in rose leaves to powdery mildew resistance
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Relation of nitrogenous substances in rose leaves to powdery mildew resistance |
| Names |
Bartlett, Allan B.
(creator) Deep, Ira W. (advisor) |
| Date Issued | 1963-04-26 (iso8601) |
| Note | Graduation date: 1963 |
| Abstract | There is considerable variation among rose varieties in susceptibility to mildew, and as a result of maturation, leaves of most susceptible varieties become resistant to infection. The nature of resistance has been sought in various studies involving environmental, morphological, and physiological factors. An attempt was made in the present investigation to correlate rose mildew resistance with levels of nitrogenous compounds in the leaves. Extracts from young and old leaves from three susceptible varieties, White Knight, Nocturne, and Poinsettia, and three resistant rose varieties, Pink Favorite, Tropicana, and Sarabande, and from diseased leaves from the susceptible varieties were analyzed by paper chromatography. The data presented represent the results from processing 53 paper chromatograms and analysis of four extracts with an Amino Acid Analyzer. At least two chromatograms were processed for each extract which was used for quantitative determinations. Thirty-two ninhydrin reactive compounds were found in the rose leaf tissues. Twenty-six were found on chromatograms and six others were detected with an Amino Acid Analyzer. Substances on the chromatograms were identified by comparison with maps prepared from known substances and by the use of specific developing reagents. Twenty-nine of the nitrogenous substances were identified; three are listed as unknown compounds. Quantitative determinations, based upon spot size and intensity of color reaction, were carried out on 22 amino compounds. The amino compounds in leaves of susceptible as compared with resistant varieties and in young leaves as compared with old leaves which have become resistant with age are correlated with susceptibility of these tissues to mildew. ß-Alanine, tyrosine, pipecolic acid, and lysine were usually found in higher amounts in susceptible tissues than in corresponding resistant tissues. Cysteic acid was found in relatively high levels in resistant varieties and in old leaves. The low levels of certain compounds in resistant tissues suggests a requirement for these materials by the pathogen. The high concentration of cysteic acid could reflect a lack of adequate cysteine for growth of the pathogen, since inhibition of cysteine synthesis could lead to a build-up of cysteic acid. Certain combinations of amino compounds were found to be more highly concentrated in susceptible than in resistant tissues. The level of total amino compounds also tended to be higher in susceptible tissues. Inhibition of the pathogen may be due not only to lower levels of available nitrogenous compounds in resistant tissues, but also to the proportion of such compounds to one another. Healthy tissues from all three varieties contained higher levels of amino compounds than corresponding diseased tissues. Six of the eight amino compounds which decreased in diseased leaves were also found in lower concentrations in old leaves. This may suggest that certain amino compounds are particularly important in nutrition of the pathogen. There appears to be a strong correlation between amino compound levels and resistance to mildew. It is suggested that the concentrations of amino compounds influence host resistance through requirements of the rose mildew pathogen for these substances, or that the presence of the amino compounds may reflect the type of metabolism which occurs in resistant tissue. |
| Genre | Thesis/Dissertation |
| Topic | Erysiphaceae |
| Identifier | http://hdl.handle.net/1957/48912 |
